Printing ink



Patented Mar. 25, 1941 UNITED STATES PATENT OFFICE PRINTING INK No Drawing. Application August 11, 1939, Serial No. 289,593

2 Claims.

This invention relates to printing inks of the type especially suitable for high speed intaglio or rotognavure printing, and more particularly to such inks which are rapidly drying and contain mixtures of asphalts, gilson'ite and the likewith fast evaporating solvents.

In the past, rotogravure inks have been almost universally compounded of body or binder materials such as gilsonite, asphalts, gums and the like dissolved in aromatic hydrocarbon solvents such as benaol and toluol. These solvents present the disadvantage of being extremely toxic and hazardous to the health of the workmen, but their use has been continued because of the lack of other solvents in a commercially feasible price range, which would operate satisfactorily to produce all the qualities necessary in an ink of this type.

available in superabundance and ingeneral usage and even cheaper than the aromatics, were unsatisfactory in having a limited solvent power for most of the suitable binders for such Moreover, composition-s having a high percentage of petroleum solvents, exhibited very poor drying due to slow solvent release, resulting in a tacky, sticky film or impression, subject to smearing, offsetting and other troubles.

Other common orgamc solvents which were suitable in characteristics were economically unsuitable because of their high prices.

One of the objects of the present invention is to provide a printing ink of the intaglio type which is capable of satisfactory printing at the 5 highest speeds used in the printing act with the prior art inks but is free from the toxic characteristics of commercial cotogravure inks.

Another object of the invention is the preparation of such inks with the use of non-toxic soi- 40 vents which evaporate rapidly and with th rapid solvent release to produce a hard, non-tacky, nonsm-earing, non-offsetting film.

A further object is to prepare such inks at a cost comparable to that of the prior art commercial inks.

Other objects and advantages of the invention will be apparent from the description thereof and the appended claims.

I have discovered that although, as long lmow-n, 50 petroleum naphthas from their inherent characteristics are unsuited for use, as such, as the solvent portion of a. rot-ognavure ink,'neve1'theless, nitro-parafiines may be so combined with certain petroleum naphthas as to provide a very satisfactory solvent to be used with asphalt, gil- The petroleum hydrocarbons, while readily sonite, and bituminous mixtures such as heretofore used in the formation of intagli-o ink-s. The nitro-parafiines have a high surface tension and the capacity to impart to the petroleum naphthas of properly coordinated range of carbon atom 5 content and boiling point, at least as good solvent ohauacteristics as benzol has with respect to the g-ilsonite, etc, binders, so that the mixture of nitro-pamafiine and petroleum naphtha becomes an excellent solvent for material of bitu- 10 minous nature, like the gilsom'te and asphalts, and this desirable solvent capacity is attamed without the attendant toxicity hazards present in benzol and the like, heretofore generally used in such inks.

By properly selecting the nitro-paraffine with respect to the petroleum naphtha, the volatility of the mixture as well as the surface tension thereof may be greater than that of benzol if desired. The non-toxic and volatile properties 20 of the petroleum naphtha may be fully taken advantage of by the selection of a nitro-paraffine of similar non-toxic properties and of such character that the mixture will have great volatility, so that the highest printing speeds used in the 25 art may be readily attained.

I have found that very satisfiactory practical operating results may be attained by providing an ink which contains by weight of gilsonite in solution and which has a viscosity of 30 from 1 5 to centipoises at ordinary room temperalture of 25 0. Such a solution is a very satisfactory ink for use in the intaglio process. Such an ink solution may be obtained by using a solvent conbaining to of the selected 35 petroleum naphtha and 20% to 5% of nitroparafline, and dissolving gilsonite insuch solution to give a gilsom'te content of 10% to 35% by weight in the solution. Th nttro-parafiine may be employed in larger amounts as required 40 for special purposes.

The following example is an illustration of a satisfactory ink formula. of my invention- Weight Percent Gilsonite 33 Petroleum naphtha (B. P. 58 -85" C.) 62 Nitromethane 5 Other nitro-parafflnes of similar high volatility may be used, such as nitro-ethane and nitro-propane. And petroleum naphthas having a boiling point of the order of 58-125 C. may be 65 used. The solvent constituents may be thus admixed to give an ink having an evaporating range of the order of 100 C. or substantially below which is suitable for the high printing speeds stated above.

The composition such as stated in the example above has a viscosity of 46 centipoises at 25 C. and is suitable for printing speeds of 1000 to 1400 feet per minute. By increasing or decreasing the proportion of solvent printing speeds may be correspondingly increased or decreased if desired.

The gilsonite referred to may be replaced in part or in whole by asphalt such as generally used in the intaglio printing ink field. And also natural and residual asphalts of known kind may be used. Also pigments or extenders may be used in order to alter the color or intensity of color or opacity as required and to produce ink of the desired properties.

While the above sets forth a preferred embodiment for the practicing of my invention, it is to be understood that departures may be made therefrom within the scope of the invention as described and claimed.

What is claimed is:

1. An ink of the character described comprising as a major body or binder constituent a solution comprising up to by weight of one of the class of asphalt materials consisting of gilsonite,

asphalts, or mixtures thereof, dissolved in a mixed solvent having substantially as good solvent characteristics as benzol for said gilsonite, asphalt, or mixtures thereof, said solvent comprising from 80-95% of petroleum naphtha having a boiling range of 58-125 C. and from 205% of nitroparafiin having a boiling temperature comparable to the boiling range of the petroleum naphtha, said solvent material being selected to give the solution a viscosity of the order of not more than 50 centipoises at 25 C.

2. An ink of the character described comprising as a major body or binder constituent a solution comprising up to 35% by weight of one of the class of asphalt materials consisting of gilsonite, asphalts, or mixtures thereof, dissolved in a mixed solvent having substantially as good solvent characteristics as benzol for said gilsonite, asphalt, or mixtures thereof, said solvent comprising from -95% of petroleum naphtha having a boiling range of 58-125 C. and from 20-5% of nitroparafiin having a boiling temperature comparable to the boiling range of the petroleum naphtha, said nitroparaflin being one of a group consisting of nitromethane, nitroethane and nitropropane, said solvent material being selected to give the solution a viscosity of the order of not more than 50 centipoises at 25 C.

CLARENCE E. IRION. 

